Late Night Noodling

[Pantherjon]

Title kind of sums it up..Last night after watching my share of TV I was restless and not a bit tired so I decided to do some fiddling on RockSim and see what came out of it..

What I cam up with is a tube fin/ring tail thing that I called Ring A Ding Ding(don't know why, it just sounded appropriate at the time)..It is a little different from most tube fins, where the tube fins are a smaller diameter then the central body tube, and this one the outer tubes are bigger then the central tube..The central tube is BT-20, outer tubes are BT-50 and the ring tail is BT-80..Then I added a couple of tubes(BT-5) up front with a conical nose cone..And for added strangeness I added a couple of fins in the back for good measure!:lol:

It sims out pretty well..Weird thing tho, I take the same design, subtract the fins and it goes unstable..hmmm..

I am in the process of putting the parts together right now and once assembled I will take 'real world' measurements(weight and CG) and plug them in the RS file for a real picture on it's stability-or a better picture before I actually fly it..

Oh, and yeah, I saw the clustering option as well with those outboard BT-50's just yelling to have 'D' motors stuck in them!:lol: So I have simmed it as a cluster with a central 18mm and 2 outboard 24mm's! Will hopefully have a final RS file to post and pictures of the real thing a Ring A Ding Ding!:rotflol:

 

[Kaycee]

Interesting design!

Where I come from, noodling is a type of fishin'.

 

[sandog]

Interesting design!

Where I come from, noodling is a type of fishin'.

That's not fishing, that's trying to get a snapping turtle to bite your finger off!

 

[Kaycee]

That's not fishing, that's trying to get a snapping turtle to bite your finger off!

(OT): That's a risk that has to be taken in to consideration. I still have all my fingers.

On Topic: Nice design! Build it, fly it and then kit it!

 

[jj94]

Looks unusual in a very good way. Oh, and you said that you're thinking about putting D's in the out boards. I would advise against that because by adding motors in the out boards, you're taking away the effectiveness of the tube fins and you're also adding a lot of weight in the back.

 

[Pantherjon]

Looks unusual in a very good way. Oh, and you said that you're thinking about putting D's in the out boards. I would advise against that because by adding motors in the out boards, you're taking away the effectiveness of the tube fins and you're also adding a lot of weight in the back.

Yeah, was just some wild 'tinkering' on the outboard 'D's..But, man it sure gets up there in the sim! 1373' on a C6-5,D12-0,D12-0 combination as opposed to 607' on just the C6-5 by itself!

I have all the parts put together and have just now installed the shock cord..Once the glue dries I will put it on the scale and take a couple of pictures

 

[powderburner]

Restless, huh? Not a bit tired? Wide awake? (Are you sure?---just kidding!)

You certainly have something interesting there. jj94 is sort of correct, you would indeed have to be careful about putting a pair of Ds in the back end, but if the c.g. moves too far aft you still have other choices (as long as the design is still on paper).

You could add a bit more aft fin area, or another set of tube fins. Don't overlook the option to add a bit of nose ballast (which would be more effective in a rocket like yours with a long nose).

My own preference would be to make sure those added motors provide some backup ejection gas, in case your cluster leaves the pad with the central motor unlit. (That would be bad.) Do you have any way to add some cross-porting to bring ejection gasses from the outboard Ds into the center BT? (or would that ruin the "look" you are going for?)

Keep us posted!

 

[Pantherjon]

Well, got the recovery system installed! A 12" chute..Man that is a tight fit! And put it on the scale..A bit lighter then what RS predicted..It weighs 1.3oz with RS predicting a weight of 1.78oz..And I know why..In order to make the tube fins 'motor mounts' I had to place an 'inside tube' in them and mark them as motor mounts..As I don't really have an 'inside tube' in the outboard pods/tube fins there is the weight difference..Tho my CG IS back by about 1.5" from what RS predicted, but still over a 2 caliber margin with a single C6 in the main pipe..

Here is Ring A Ding Ding getting weight check:lol:

 

[adrian]

It sims out pretty well..Weird thing tho, I take the same design, subtract the fins and it goes unstable..hmmm..

This is not all that weird. The fins are in the same plane as the tubes at the nose. Those tubes act to destabilise the rocket; the fins compensate. Lose the fins and the nose-mounted tubes will make the rocket unstable.

Oh, and yeah, I saw the clustering option as well with those outboard BT-50's just yelling to have 'D' motors stuck in them!:lol: So I have simmed it as a cluster with a central 18mm and 2 outboard 24mm's!

As powderburner says, that will have the double effect of making the BT-50's useless as tube fins while adding a lot of weight to the rear. Make sure your sim of this cluster no longer regards the BT-50's as tube fins. I'd be surprised if the rocket is stable unless you add extra fins or extra nose weight, preferably both to compensate for the loss of fins and gain of tail weight. Another possibility might be to stick some BT-5 to the inside of each BT-50, then put a couple of 13mm motors in the BT-5 tubes. You still get your cluster, the BT-50's still have some tube fin effect, and the 13mm motors won't add as much tail weight as 24mm motors.

 

[DexterLB]

Very nice design!
Congradulations for the good job!

 

[Pantherjon]

Thanks for all the comments After a long consultation with the R&D Department I have decided to not utilize the outboard tubes as motor mounts..It will greatly reduce the stability of the rocket and I don't want to take that risk- however it would be cool seeing it go up on those 3 columns of fire:lol:

Also, one of the other considerations taken into account for this decision is the altitude attained by the cluster of motors..Being a fairly small rocket tracking will be pretty difficult-tho not impossible..

It sims nicely on a single 18mm achieving what I set out to do- to design a flyable rocket..Will have to do some real launches to validate those simulations..Hopefully I will be able to do a few test launches these next few days..

 

[jj94]

Nice build. I was surprised at how quickly you got it built though. I usually take up to a week with a build (I have to admit, I am a bit lazy...). Any ideas for paint?

 

[Pantherjon]

Nice build. I was surprised at how quickly you got it built though. I usually take up to a week with a build (I have to admit, I am a bit lazy...). Any ideas for paint?

Thanks! Yeah, I kind of surprised myself on how quickly I got it built too!:surprised: The most time consuming part was cutting the tubes..I too admit to the lazy syndrome-I have a BSD Thor I pulled out of the box a week ago and the only thing I have accomplished on it is cutting the fin slots and making a notch in the forward centering ring for the shock cord!:lol:

As far as color, haven't given it much thought..Ideas may be helpful

 

[Pantherjon]

WOO HOOO!arty: It flies! Woke up to calm skies this morning , so I grabbed the Ring A Ding Ding and pad and out to the front yard I went! I replaced the chute with a 1" wide Hartle streamer...Stuck an A8-3 in it and let 'er rip! Flew nice..Was a little bit of a corkscrew on the way up..Recovery was awesome even with it kicking the motor out with the shotgun ejection charge the laundry came out and it landed no more then 3' from the pad! Upon post flight inspection I noticed that one of the fins is slightly off on the vertical axis by about 2-3 degrees, which is what caused the slight spinning on ascent..But I am happy!

Tho I think RockSim is very generous on it's predicted altitude..lol..Sim showed an A8-3 taking it 170', it MAY have gone 100'..But it was an awesome flight..I will try to video future flights..

 

[Pantherjon]

Well, took Ring A Ding Ding out for it's second flight this morning! And caught it on video this time! Well, most of it anyway-such great skills as videographer I don't have:lol: Anyway, seems as soon as I punched the 'GO' button the wind picked up, from the OPPOSITE direction it usually does(typical)..The only problem was the laundry didn't deploy I think I got a clump of dog barf that didn't cooperate when I stuck it in the tube..Rocket tried to do a lawn core sample but thanks to the motor kicking out, it was too light to do that..Only damage was a slight crinkle at the very end of the BT which I have straightened out and re-enforced with some CA...

Anyways, here is the video..I can hear ya now, right after the rocket leaves the pad "Where'd it go?"..:lol:

 

[mach66]

Nice idea Jon, Do I smell a version 1.1 upgrade to 24mm?

Brent

 

[Pantherjon]

Nice idea Jon, Do I smell a version 1.1 upgrade to 24mm?

Brent

Keen senses you have Brent! As a matter of fact I was JUST thinking of that very same thing!:bandit: Am going to do some tinkering in RockSim and see how it plays out...

I flew R.A.D.D. again this morning with much better results-didn't bother with the video..Flew arrow straight, laundry deployed, motor casing stayed in the tube, fairly uneventful recovery-it bounced off the cable line and put a small dent in the ring fin..And reached a higher altitude then the 2 previous launches, close to the RS predicted 170' on an A8-3..

Still trying to come up with a paint scheme tho...

 

[Pantherjon]

Well, did some more 'late night noodling' after work the other night on the 24mm version of R.A.D.D. and came up with Bing A Ding Ding(B.A.D.D.):lol:

It sims nicely on almost all available motors/loads in the 24mm family..Best for a soft deployment of the laundry is the F21W-4 with deployment velocity of 7 ft/sec and an altitude of 1555 ft..The Apogee E6-4 lofts it to 1732 feet thanks to it's 6 second burn time, tho deployment speed is a tad high at 33 ft/sec..

Here are a couple of pics When I build it I think I am going to 'dress up' the ring fin some..

 

[blackjack2564]

Just a thought....why not cut the front edge of the forward 2 tubes at a 45 degree angle. Make it look like it's going fast,just sitting there!

 

[Pantherjon]

Just a thought....why not cut the front edge of the forward 2 tubes at a 45 degree angle. Make it look like it's going fast,just sitting there!

That is an idea I was thinking of as well! Great minds and all that..lol..Was actually thinking of making it like a scallop or curved cut..Was also thinking of doing pretty much the same thing on the front of the lower tube fins and having some curves incorporated into the ring fin as well..Pretty much(but probably not as drastic) as what I did with Das Hoopty..

Das Hoopty(to jog memories..lol)

 

[Pantherjon]

Guess I like diggin up the older stuff.:lol:

Anyways I got R.A.D.D. painted tonight! Was in Waldo World and saw this really cool color cap on a can of Krylon and thought this would look good on it..And it does! The Red RADD!

https://i156.photobucket.com/albums/t21/Pantherjon/NewDesign002.jpg
Official name of the color is Cherry Red..And it looks even better then the picture shows..You just gotta see it in the sun!

 

[Stormbringer]

Nice.